In general, a fuel pump of a vehicle is mounted on the inside of a fuel tank of the vehicle and serves to suction fuel and pressure-feed the suctioned fuel to a fuel injection device mounted in an engine.
In addition, the fuel pump for the vehicle is classified into a mechanical fuel pump and an electrical fuel pump and a turbine fuel pump 10 which is a type of electrical fuel pump is primarily used in an engine using gasoline as fuel.
In the turbine fuel pump 10, a driving motor 20 is provided in a motor housing 60 of the fuel pump 10, an upper casing 30 and a lower casing 40 are provided on a lower end part of the motor housing 60 to be closely attached to each other, and an impeller 50 is interposed therebetween as shown in FIG. 1.
In addition, the impeller 50 is joined to a rotational shaft 21 of a driving motor 20, such that the impeller 50 is configured to rotate with the driving motor 20.
That is, as the impeller 50 rotates, a pressure difference is generated, and as a result, fuel is suctioned into the impeller 50 and while the pressure of fuel is increased by a rotation flow generated by continuous rotation of the impeller 50, fuel is discharged.
Therefore, fuel is introduced into a fuel suction port 41 of the lower casing 40 to flow to a check valve 70 formed in an upper part of the motor housing 60 along an inner part of the motor housing 60 through a fuel discharge port 31 of the upper casing 30 with the pressure thereof increased through the rotating impeller 50 and supplied to the fuel injection device mounted on the engine of the vehicle.
In this case, the impeller 50 is formed in a disk shape, a plurality of blades 51 are formed on an circumferential surface thereof in an outer direction of the circumferential surface, blade chambers 52 are formed among respective blades 51 to penetrate through both surfaces of the impeller 50 as shown in FIG. 2, such that fuel is introduced and discharged individually in an upper part and a lower part of the blade chamber 52 and fuel is introduced into the fuel suction port 41 of the lower casing 40 to generate the rotation flow in a space between a blade chamber 52 and a lower channel groove 42 formed in the lower casing 40 and an upper channel groove 32 formed in the upper casing 30 as shown in FIG. 3, and a circulation process in which fuel is again introduced into the neighboring blade chamber 52 to generate the rotation flow is repeated. Therefore, kinetic energy generated by the rotation of the impeller 50 is converted into pressure energy of fuel, and as a result, fuel is delivered to the fuel discharge port 31 of the upper casing 30.
In addition, in the impeller 50 in the related art, a circumference center guide 53 is formed at the center of the circumferential surface along the circumferential surface of the impeller 50 so as to efficiently generate the rotation flow formed in the space between the blade chamber 52 and the lower channel groove 42 and the rotation flow generated in the space between the impeller chamber 52 and the upper channel groove 32.
In this case, as shown in FIG. 4, the fuel that flows along the upper channel groove 32 of the upper casing 30 is discharged through the fuel discharge port 31. However, the fuel that flows along the lower channel groove 42 of the lower casing 40 should be discharged through the fuel discharge port 31 by passing through the blade chamber 52 of the impeller 50.
Therefore, the fuel that flows along the lower channel groove 42 hits the blade 51 of the impeller 50 and passes through the blade chamber 51 to interrupt the flow of the rotation flow, thereby causing loss of a fuel movement amount and further, serve as flow resistance of fuel to make the pressure of the fuel pump instable and deteriorate performance.
Further, with a current technological tendency in which components in the vehicle are gradually subjected to a light weight, a compact size, and high performance in order to satisfy user's various preferences globally, a study about high performance of even the fuel pump has been required.
In addition, performance of the fuel pump is determined according to a specification of the vehicle and high efficiency is required as a recent trend. Therefore, the turbine fuel pump for a vehicle in the related art is limitative in increasing a discharge amount of fuel under high pressure.